Problem: Rewrite as a simplified fraction. ${3.5\overline{8} = {?}}$
Explanation: Let $x$ equal the decimal. Set up two equations such that the digits after the decimal point are identical. ${\begin{align*}100x &= 358.8888...\\ 10x &= 35.8888...\end{align*}}$ Subtracting the two equations, we have: ${90x = 323}$ ${x = \dfrac{323}{90}} \text{or} {3 \dfrac{53}{90}}$